Uses for amino acid anticonvulsants

ABSTRACT

The present invention is directed to the use of compounds of the formula: 
                         
for treating pain, in particular neuropathic pain, bipolar disease and migraine headaches.

RELATED APPLICATION

The present application is a divisional application of U.S. patentapplication Ser. No. 09/938,677 filed on Aug. 24, 2001 now U.S. No.6,884,910, which is claiming benefit of provisional application havingU.S. Ser. No. 60/228,230 filed on Aug. 25, 2000.

FIELD OF THE INVENTION

The present invention is directed to the novel uses of a peptide classof compounds for treating bipolar disorders and headaches, such asmigraines and pain, especially neuropathic pain.

BACKGROUND OF THE INVENTION

Bipolar disorders and headaches, such as migraines, and pain, includingneuropathic pain, are varied maladies that on its face, are diverse.

A migraine headache is defined as a periodically occurring vascularheadache characterized by pain in the head (usually unilateral), nausea,and vomiting, photophobia, phenophobia, vertigo and general weakness.Migraine is the most common type of vascular headache and affects asmany as 15% of the world's population. Of the different types ofmigraines, classical migraine and common migraine are the two mostprevalent. The major difference between the two types of migraines isthat classical migraines are preceded by the appearance of neurologicalsymptoms before an attack whereas common migraines are not preceded bysuch symptoms. Migraine is caused by intermittent brain dysfunction.However, the precise pathophysiological mechanisms involved are notunderstood. The head-pain is believed to involve blood vessel dilationand a reduction in the brain's pain relieving chemicals.

Neuropathic pain, on the other hand, can be described as pain associatedwith damage or permanent alteration of the central nervous system.Clinical manifestations of neuropathic pain include a sensation ofburning or electric shock, feelings of bodily distortion, allodynia andhyperalgesia.

It results from injury to a nerve. In contrast to the immediate paincaused by tissue injury, neuropathic pain can develop days or monthsafter a traumatic injury. Furthermore, while pain caused by tissueinjury is usually limited induration to the period of tissue repair,neuropathic pain frequently is long lasting or chronic.

Moreover, neuropathic pain can occur spontaneously or as a result ofstimulation that normally is not painful.

The clinical causes of neuropathic pain are widespread and include bothtrauma and disease. For example, traumatic nerve compression, or crush,and traumatic injury to the brain or spinal cord are common causes ofneuropathic pain. Furthermore, most traumatic nerve injuries also causethe formation of neuromas, in which pain occurs as a result of aberrantnerve regeneration. In addition, cancer-related neuropathic pain iscaused when tumor growth painfully compresses adjacent nerves, the brainor the spinal cord. Neuropathic pain is associated with diseases such asdiabetes or alcoholism.

Bipolar disorder is a neuropsychiatric disorder. Also known as bipolaraffective disorder (BAD) or manic-depressive illness, it ischaracterized by episodes of elevated mood (mania) and depression. Themost severe and clinically distinctive forms of BAD are BP-I (severebipolar affective (mood) disorder), which affects 2–3 million people inthe U.S. and SAD-M (schizoaffective disorder manic type). They arecharacterized by at least one full episode of mania, with or withoutepisodes of major depression (defined by lower mood or depression, withassociated disturbances in rhythmic behaviors, such as sleeping, eatingand sexual activity).

The therapies are varied. Analgesics are often used to treat infrequentand mild migraines. Analgesics reduce the pain of a migraine and in thecase of aspirin also discourage clumping of blood platelets. However,for moderate to severe migraines, stronger medication is necessary,e.g., ergotamine or 5-H-T₁ agonists, like sumatriptan.

On the other hand, for neuropathic pain, opioid compounds (opiates) suchas morphine may be utilized to treat the malady. Although effective asan analgesic, it is not always effective in treating neuropathic painand may induce tolerance in patients. When a subject is tolerant toopioid narcotics, increased doses are required to achieve a satisfactoryanalgesic effect. At high doses, these compounds produce side effects,such as respiratory depression, which can be life threatening. Inaddition, opioids frequently produce physical dependence in patients,which may be related to the dose of opioid taken and the period of timeover which it is taken by the subject.

But neuropathic pain and bipolar disorder frequently are resistant toavailable drug therapies. In addition, current therapies have seriousside-effects including, for example, cognitive changes, sedation,nausea, and in the case of narcotic drugs addictions. Many patientssuffering from neuropathic pain are elderly or have other medicalconditions that particularly limit their tolerance of the side-effectsassociated with available drug therapy.

The inadequacy of current therapy in relieving neuropathic pain andbipolar disorders without producing intolerable side-effects frequentlyis manifested in the depression and suicidal tendency of chronic painsufferers. Moreover, the present drugs are not effective for completelyalleviating the pain from those who have moderate to heavy migraineheadaches.

U.S. Pat. No. 5,885,999 discloses compounds which are useful fortreating various maladies such as pain and headaches includingmigraines. These compounds are serine derivatives of the formula:

wherein m is zero, 1 or 2; and n is zero or 1, with the proviso that thesum total of m+n is 1 or 2;

-   -   R¹ represents phenyl; naphthyl; benzohydryl; or benzyl, where        the naphthyl group or any phenyl moiety may be substituted;    -   R² represents hydrogen; phenyl; heteroaryl selected from        indazolyl, thienyl, furanyl, pyridyl, thiazolyl, tetrazolyl and        quinolinyl; naphthyl; benzohydryl; or benzyl; wherein each        heteroaryl, napthyl group and any phenyl moiety may be        substituted;    -   R³ and R⁴ each independently represents hydrogen or C₁₋₆alkyl or        R³ and R⁴ together are linked so as to form a C₁₋₃alkylene        chain;    -   Q represents CR⁵R⁶ or NR⁵;    -   X and Y each independently represents hydrogen, or together form        a group ═O; and

Z represents a bond O, S, SO, SO₂, NR^(c) or —(CR^(c)R^(d))-m whereR^(c) and R^(d) each independently represent hydrogen or C₁₋₆alkyl;

-   -   or a pharmaceutically acceptable salt thereof.

The compounds are alleged to be also useful in the treatment orprevention of inflammation, emesis and postherapeutic neuralgia.

In U.S. Pat. No. 6,228,825 to Tsai, et al., other amino acids andderivatives thereof are alleged to be useful for treatingneuropsychiatric disorders, such as schizophrenia, Alzheimer's Disease,depression, autism, closed head injury, benign forgetfulness, childhoodlearning disorders, and attention deficit disorders. These drugs include(i) D-alanine or modified form thereof, provided that the composition issubstantially free of D-cycloserine and/or (ii) serine (or a modifiedfrom thereof), and/or (iii) 105 to 500 mg of D-cycloserine (or amodified form thereof); and/or (iv) N-methylglycine (or a modified formthereof).

D-cycloserine, D-serine esters, D-serine or salts thereof have beendisclosed to be useful in treating spinocerebellar degeneration. See, EPApplication No. 1,084,704.

Peptides have also been alleged to be useful for treatment of pain andneurosis. More specifically, EPO application 997,147 discloses compoundsof the formula:

wherein R¹ is

-   -   1) C1–15 alkyl,    -   2) C1–8 alkoxy,    -   3) phenyl,    -   4) C3–8 cycloalkyl,    -   5) hetero ring,    -   6) C1–4 alkyl substituted by phenyl, C3–8 cycloalkyl, or hetero        ring,    -   7) C1–4 alkoxy substituted by phenyl, C3–8 cycloalkyl, or hetero        ring, or    -   8) C2–4 alkenyl substituted by phenyl, C3–8 cycloalkyl, or        hetero ring (with proviso that, all phenyl, C3–8 cycloalkyl and        hetero ring in R¹ group may be substituted by 1–3 substituent        selected from the following (i)–(xi):        -   (i) C1–4 alkyl,        -   (ii) C1–4 alkoxy,    -   (iii) phenyl,        -   (iv) phenoxy,        -   (v) benzyloxy,        -   (vi) —SR⁵ (in which R⁵ is hydrogen or C1–4 alkyl),        -   (vii) C2–5 acyl,        -   (viii) halogen,        -   (ix) C1–4 alkoxycarbonyl,        -   (x) nitro,        -   (xi) —NR⁵R⁷ (in which R⁶ and R⁷ each independently, is            hydrogen, C1–4 alkyl or. C1–4 alkoxycarbonyl, or R⁶ and R⁷            taken together with the nitrogen atom to which they are            attached may represent 5–7 membered saturated hetero ring            containing another one nitrogen atom or one oxygen atom));    -   A is a bond, —CO— or —SO₂—;    -   R² is hydrogen or C1–4 alkyl optionally substituted by one        phenyl;    -   D is C1–4 alkylene or C2–4 alkenylene;    -   E is        -   1) —COO—,        -   2) —OCO—,        -   3) —CONR⁸ (in which R⁸ is hydrogen or C1–4 alkyl),        -   4) —NR⁹CO— (in which R⁹ is hydrogen or C1–4 alkyl),        -   5) —O—,        -   6) —S—,        -   7) —SO—,    -   8) —SO₂—,        -   9) —NR¹⁰— (in which R¹⁰ is hydrogen or C1–4 alkyl),        -   10) —CO—,        -   11) —SO₂NR¹¹— (in which R¹¹ is hydrogen or C1–4 alkyl) or        -   12) —NR¹²SO₂— (in which R¹² is hydrogen or C1–4 alkyl);

-   R³ is    -   1) carbocyclic ring,    -   2) hetero ring, or    -   3) C1–4 alkyl substituted by carbocyclic ring or hetero ring        (with proviso that, all carbocyclic ring and hetero ring in R³        may be substituted by 1–3 substituents selected from the        following (i)–(xi);        -   (i) C1–4 alkyl,        -   (ii) C1–4 alkoxy,        -   (iii) phenyl,        -   (iv) phenoxy,        -   (v) benzyloxy,        -   (vi) —SR¹³ (in which R¹³ is hydrogen or C1–4 alkyl),        -   (vii) C2–5 acyl,        -   (viii) halogen,        -   (ix) C1–4 alkoxycarbonyl,        -   (x) nitro,        -   (xi) —NR¹⁴R¹⁵ (in which R¹⁴ and R¹⁵, each independently, is            hydrogen, C1–4 alkyl or C1–4 alkoxycarbonyl, or R¹⁴ and R¹⁵            taken together with the nitrogen atom to which they are            attached may represent 5–7 membered saturated hetero ring            containing another one nitrogen atom or one oxygen atom);

-   J is —O— or —NR¹⁶— (in which R¹⁶ is hydrogen or C1–4 alkyl);

-   R⁴ is    -   1) C1–8 alkyl,    -   2) carbocyclic ring,    -   3) hetero ring,    -   4) C1–8 alkyl substituted by 1–3 of substituent selected from        the following (i)–(v);        -   (i) carbocyclic ring,        -   (ii) hetero ring,        -   (iii) COOR¹⁷ (in which R¹⁷ is hydrogen or C1–4            alkyl-substituted by one phenyl (in which phenyl may be            substituted by C1–4 alkoxy),        -   (iv) SR¹⁸ (in which R¹⁸ is hydrogen or C1–4 alkyl),        -   (v) OR¹⁹ (in which R¹⁹ is hydrogen or C1–4 alkyl), or    -    when J represents —NR¹⁶— group, R⁴ and R¹⁶ taken together with        the nitrogen atom to which they are attached may represent        hetero ring (with proviso that, all carbocyclic ring and hetero        ring, and hetero ring represented by R⁴ and R¹⁶ taken together        with the nitrogen atom to which they are attached may be        substituted by 1–3 of substituent selected from the following        (i)–(xi);        -   (i) C1–4 alkyl,        -   (ii) C1–4 alkoxy,        -   (iii) phenyl,        -   (iv) phenoxy,        -   (v) benzyloxy,        -   (vi) —SR²⁰ (in which R²⁰ is hydrogen or C1–4 alkyl),        -   (vii) C2–5 acyl,        -   (viii) halogen,        -   (ix) C1–4 alkoxycarbonyl,        -   (x) nitro,        -   (xi) —NR²¹R²² (in which R²¹ and R²² each independently, is            hydrogen, C1–4 alkyl or C1–4 alkoxycarbonyl, or R²¹ and R²²            taken together with the nitrogen atom to which they are            attached may represent 5–7 membered saturated hetero ring            containing another one nitrogen atom or one oxygen atom),            non-toxic salt thereof, or a hydrate thereof.

Other peptides are known to exhibit central nervous system (CNS)activity and are useful in the treatment of epilepsy and other CNSdisorders. These peptides, which are described in U.S. Pat. No.5,378,729, to Kohn, et al., have the formula:

wherein

-   -   R is hydrogen, lower alkyl, lower alkenyl, lower alkynyl, aryl,        aryl lower alkyl, heterocyclic, heterocyclic lower alkyl, lower        alkyl heterocyclic, lower cycloalkyl, lower cycloalkyl lower        alkyl, and R is unsubstituted or is substituted with at least        one electron withdrawing group or electron donating group;    -   R₁ is hydrogen or lower alkyl, lower alkenyl, lower alkynyl,        aryl lower alkyl, aryl, heterocyclic lower alkyl, heterocyclic,        lower cycloalkyl, lower cycloalkyl lower alkyl, each        unsubstituted or substituted with an electron donating group or        an electron withdrawing group; and    -   R₂ and R₃ are independently hydrogen, lower alkyl, lower        alkenyl, lower alkynyl, aryl lower alkyl, aryl, heterocyclic,        heterocyclic lower alkyl, lower alkyl heterocyclic, lower        cycloalkyl, lower cycloalkyl lower alkyl, or Z—Y wherein R₂ and        R₃ may be unsubstituted or substituted with at least one        electron withdrawing group or electron donating group;    -   Z is O, S, S(O)_(a), NR₄, PR₄ or a chemical bond;    -   Y is hydrogen, lower alkyl, aryl, aryl lower alkyl, lower        alkenyl, lower alkynyl, halo, heterocyclic, heterocyclic lower        alkyl, and Y may be unsubstituted or substituted with an        electron donating group or an electron withdrawing group,        provided that when Y is halo, Z is a chemical bond, or    -   ZY taken together is NR₄NR₅R₇, NR₄OR₅, ONR₄R₇, OPR₄RS, PR₄OR₅,        SNR₄R₇, NR₄SR₇, SPR₄R, or PR₄SR₇, NR₄PR₄R₅R₆ or PR₄NR₅R₇;

-   -   R₄, R₅ and R₆ are independently hydrogen, lower alkyl, aryl,        aryl lower alkyl, lower alkenyl, or lower alkynyl, wherein R₄,        R₅ and R₆ may be unsubstituted or substituted with an electron        withdrawing group or an electron donating group; and    -   R₇ is R₆ or COOR₈ or COR₈;    -   R₈ is hydrogen or lower alkyl, or aryl lower alkyl, and the aryl        or alkyl group may be unsubstituted or substituted with an        electron withdrawing group or an electron donating group; and    -   n is 1–4; and    -   a is 1–3.

U.S. Pat. No. 5,773,475, the contents of which are incorporated byreference, also discloses additional compounds useful for treating CNSdisorders. These compounds are N-benzyl-2-amino-3-methoxy-propionamideshaving the formula:

wherein

-   -   Ar is aryl which is unsubstituted or substituted with halo;    -   Q is lower alkoxy; and    -   Q₁ is CH₃.

Harris in U.S. Pat. No. 6,133,261 describes a method of treating orpreventing stroke in a human by administering thereto an effectiveamount of a compound of the formula:R—NH—[—C(═Q)—C(R₂)(R₃)—NH—]_(n)—C(═A)R₁wherein

-   -   R is hydrogen, lower alkyl, lower alkenyl, lower alkynyl, aryl,        aryl (lower alkyl), heterocyclic, heterocyclic (lower alkyl),        (lower alkyl) heterocyclic, lower cycloalkyl, lower cycloalkyl        (lower alkyl), and R is unsubstituted or is substituted with at        least one electron withdrawing group, or electron donating        group;    -   R₁ is hydrogen or lower alkyl, lower alkenyl, lower alkynyl,        aryl (lower alkyl), aryl, heterocyclic, (lower alkyl)        heterocyclic, heterocyclic (lower alkyl), lower cycloalkyl,        lower cycloalkyl (lower alkyl), each unsubstituted or        substituted with an electron donating group or an electron        withdrawing group and    -   R₂ and R₃ are independently hydrogen, lower alkyl, lower        alkenyl, lower alkynyl, aryl (lower alkyl), aryl, heterocyclic,        heterocyclic (lower alkyl), (lower alkyl) heterocyclic, lower        cycloalkyl, lower cycloalkyl (lower alkyl), SO₃ ⁻, or Z—Y where        R₂ and R₃ may be unsubstituted or substituted with at least one        electron withdrawing group or electron donating group;    -   Z is O, S, S(O)_(a), NR₄, PR₄ or a chemical bond;    -   Y is hydrogen, lower alkyl, aryl, aryl(lower alkyl), lower        alkenyl, lower alkynyl, halo, heterocyclic, heterocyclic (lower        alkyl), (lower alkyl)heterocyclic, cycloalkyl, cycloalkyl (lower        alkyl) and Y may be unsubstituted or substituted with an        electron donating group or an electron withdrawing group,        provided that when Y is halo, Z is a chemical bond;    -   or ZY taken together is NR₄NR₅R₇, NR₄OR, ONR₄R₇, OPR₄R₅, PR₄OR₅,        SNR₄R₇, NR₄SR₇, SPR₄R₇, PR₄SR₇, NR₄RP₅R₆, PR₄NR₅R₇, NR₄C(O)R₅,        SC(O)R₅, NR₄CO₂R₅, SCO₂R₅, NR₄C(O)RSR₅C(═A) OR₆, or        NR₄C(O)NR₅S(O)_(a)R₆, NR₄C(S)R₅R₆, NR₄C(═Q)MNR₅C(═A)OR₆, or        C(S)NH₂;    -   R₄, R₅ and R₆ are independently hydrogen, lower alkyl, aryl,        aryl (lower alkyl), lower alkenyl, or lower alkynyl, wherein R₄,        R₅ and R₆ may be unsubstituted or substituted with an electron        withdrawing group or an electron donating group;    -   R_(8 is) R₆, COOR₈, or C(O)R₈;    -   R₈ is hydrogen or lower alkyl, or aryl (lower alkyl), and the        aryl or alkyl group may be unsubstituted or substituted with an        electron withdrawing group or an electron donating group;    -   A and Q are independently O or S;    -   M is an alkylene chain containing up to 6 carbon atoms or a        chemical bond;    -   n is 1–4; and    -   a is 1–3;    -   or a pharmaceutically acceptable salt thereof.

The present inventor has found that these peptides in U.S. Pat. Nos.5,378,729 and 5,773,475, are useful for treating pain, includingneuropathic pain, and headaches, including migraines and bipolardisorders. Moreover, these compounds are not addictive and do notexhibit the side effects of the commercially available drugs describedhereinabove.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to the method of treatingbipolar disease in a patient suffering from same which comprisesadministering thereto an amount effective to treat such bipolar diseaseof a compound having Formula I:

wherein

-   -   R is hydrogen, lower alkyl, lower alkenyl, lower alkynyl, aryl,        aryl lower alkyl, heterocyclic, heterocyclic lower alkyl, lower        alkyl heterocyclic, lower cycloalkyl, lower cycloalkyl lower        alkyl, and R is unsubstituted or is substituted with at least        one electron withdrawing group, or electron donating group;    -   R₁ is hydrogen or lower alkyl, lower alkenyl, lower alkynyl,        aryl lower alkyl, aryl, heterocyclic lower alkyl, heterocyclic,        lower alkyl heterocyclic, lower cycloalkyl, lower cycloalkyl        lower alkyl, each unsubstituted or substituted with an electron        donating group or an electron withdrawing group; and    -   R₂ and R₃ are independently hydrogen, lower alkyl, lower        alkenyl, lower alkynyl, aryl lower alkyl, aryl, heterocyclic,        heterocyclic lower alkyl, lower alkyl heterocyclic, lower        cycloalkyl, lower cycloalkyl lower alkyl, halo or Z—Y wherein R₂        and R₃ may be unsubstituted or substituted with at least one        electron withdrawing group or electron donating group;    -   Z is O, S, S(O)_(a), NR₄, or PR₄;    -   Y is hydrogen, lower alkyl, aryl, aryl lower alkyl, lower        alkenyl, lower alkynyl, halo, heterocyclic, heterocyclic lower        alkyl, lower alkyl heterocyclic, lower cycloalkyl, lower        cycloalkyl lower alkyl, and Y may be unsubstituted or        substituted with an electron donating group or an electron        withdrawing group, or    -   ZY taken together is NR₄NR₅R₇, NR₄OR₅, ONR₄R₇, OPR₄R₅, PR₄OR₅,        SNR₄R₇, NR₄SR₇, SPR₄R₅ or PR₄SR₇, NR₄PR₅R₆ or PR₄NR₅R₇,

-   -   R₄, R₅ and R₆ are independently hydrogen, lower alkyl, aryl,        aryl lower alkyl, lower alkenyl, or lower alkynyl, wherein R₄,        R₅ and R₆ may be unsubstituted or substituted with an electron        withdrawing group or an electron donating group;    -   R₇ is independently R₆ or COOR₈ or COR₈;    -   R₈ is hydrogen or lower alkyl, or aryl lower alkyl, and the aryl        or alkyl group may be unsubstituted or substituted with an        electron withdrawing group or an electron donating group; and    -   n is 1–4; and    -   a is 1–3.

The present invention is also directed to the method of treating pain ina patient suffering from same which comprises administering to saidpatient a pain alleviating effective amount of said compound to treatthe pain.

In another aspect, the present invention is directed to a method oftreating headaches, including migraine headaches, in a patient sufferingfrom same which comprises administering to said patient a headachealleviating effective amount of said compound.

DETAILED DESCRIPTION OF THE INVENTION

As indicated hereinabove, the compounds of Formula I are useful fortreating pain, including neuropathic pain and headaches, includingmigraine headaches, and bipolar disorders. These compounds are describedin U.S. Pat. No. 5,378,729, the contents of which are incorporated byreference.

As defined herein, the “alkyl” groups when used alone or in combinationwith other groups, are lower alkyl containing from 1 to 6 carbon atomsand may be straight chain or branched. These groups include methyl,ethyl, propyl, isopropyl, butyl, isobutyl, tertiary butyl, amyl, hexyl,and the like.

The “aryl lower alkyl”; groups include, for example, benzyl, phenethyl,phenpropyl, phenisopropyl, phenbutyl, diphenylmethyl, 1,1-diphenylethyl,1,2-diphenylethyl, and the like.

The term “aryl”, when used alone or in combination, refers to anaromatic group which contains from 6 up to 18 ring carbon atoms and upto a total of 25 carbon atoms and includes the polynuclear aromatics.These aryl groups may be monocyclic, bicyclic, tricyclic or polycyclicand are fused rings. A polynuclear aromatic compound, as used herein, ismeant to encompass bicyclic and tricyclic fused aromatic ring systemscontaining from 10–18 ring carbon atoms and up to a total of 25 carbonatoms. The aryl group includes phenyl, and the polynuclear aromaticse.g., naphthyl, anthracenyl, phenanthrenyl, azulenyl and the like. Thearyl group also includes groups like ferrocyenyl.

“Lower alkenyl” is an alkenyl group containing from 2 to 6 carbon atomsand at least one double bond. These groups may be straight chained orbranched and may be in the Z or E form. Such groups include vinyl,propenyl, 1-butenyl, isobutenyl, 2-butenyl, 1-pentenyl, (Z)-2-pentenyl,(E)-2-pentenyl, (Z)-4-methyl-2-pentenyl, (E)-4-methyl-2-pentenyl,pentadienyl, e.g., 1,3- or 2,4-pentadienyl, and the like.

The term “lower alkynyl” is an alkynyl group containing 2 to 6 carbonatoms and may be straight chained as well-as branched. It includes suchgroups as ethynyl, propynyl, 1-butynyl, 2-butynyl, 1-pentynyl,2-pentynyl, 3-methyl-1-pentynyl, 3-pentynyl, 1-hexynyl, 2-hexynyl,3-hexynyl and the like.

The term “lower cycloalkyl” when used alone or in combination is acycloalkyl group containing from 3 to 18 ring carbon atoms and up to atotal of 25 carbon atoms. The cycloalkyl groups may be monocyclic,bicyclic, tricyclic, or polycyclic and the rings are fused. Thecycloalkyl may be completely saturated or partially saturated. Examplesinclude cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl, cyclodecyl, cyclohexenyl, cyclopentenyl, cyclooctenyl,cycloheptenyl, decalinyl, hydroindanyl, indanyl, fenchyl, pinenyl,adamantyl, and the like. Cycloalkyl includes the cis or trans forms.Furthermore, the substituents may either be in endo or exo positions inthe bridged bicyclic systems.

The term “electron-withdrawing and electron donating” refer to theability of a substituent to withdraw or donate electrons, respectively,relative to that of hydrogen if the hydrogen atom occupied the sameposition in the molecule. These terms are well understood by one skilledin the art and are discussed in Advanced Organic Chemistry, by J. March,John Wiley and Sons, New York, N.Y., pp. 16–18 (1985) and the discussiontherein is incorporated herein by reference. Electron withdrawing groupsinclude halo, including bromo, fluoro, chloro, iodo and the like; nitro,carboxy, lower alkenyl, lower alkynyl, formyl, carboxyamido, aryl,quaternary ammonium, trifluoromethyl, aryl lower alkanoyl, carbalkoxyand the like. Electron donating groups include such groups as hydroxy,lower alkoxy, including methoxy, ethoxy and the like; lower alkyl, suchas methyl, ethyl, and the like; amino, lower alkylamino, di(loweralkyl)amino, aryloxy such as phenoxy; mercapto, lower alkylthio, disulfide(lower alkyldithio) and the like. One of ordinary skill in the art willappreciate that some of the aforesaid substituents may be considered tobe electron donating or electron withdrawing under different chemicalconditions. Moreover, the present invention contemplates any combinationof substituents selected from the above-identified groups. The term“halo” includes fluoro, chloro, bromo, iodo and the like.

The term “acyl” includes lower alkanoyl.

As employed herein, the heterocyclic substituent contains at least onesulfur, nitrogen or oxygen ring atom, but also may include one orseveral of said atoms in the ring, but preferably no more than 4heteroatoms in the ring. The heterocyclic substituents contemplated bythe present invention include heteroaromatics and saturated andpartially saturated heterocyclic compounds. These heterocyclics may bemonocyclic, bicyclic, tricyclic or polycyclic and are fused rings. Theymay contain from 3 up to 18 ring atoms and up to a total of 17 ringcarbon atoms and a total of up to 25 carbon atoms. The heterocyclics arealso intended to include the so-called benzoheterocyclics.Representative heterocyclics include furyl, thienyl, pyrazolyl,pyrrolyl, imidazolyl, indolyl, thiazolyl, oxazolyl, isothiazolyl,isoxazolyl, piperidyl, pyrrolinyl, piperazinyl, quinolyl, triazolyl,tetrazolyl, isoquinolyl, benzofuryl, benzothienyl, morpholinyl,benzoxazolyl, tetrahydrofuryl, pyranyl, indazolyl, purinyl, indolinyl,pyrazolindinyl, imidazolinyl, imadazolindinyl, pyrrolidinyl, furazanyl,N-methylindolyl, methylfuryl, pyridazinyl, pyrimidinyl, pyrazinyl,pyridyl, epoxy, aziridino, oxetanyl, azetidinyl, the N-oxides of thenitrogen containing heterocycles, such as the nitric oxides of pyridyl,pyrazinyl, and pyrimidinyl and the like. The preferred heterocyclics arethienyl, furyl, pyrrolyl, benzofuryl, benzothienyl, indolyl,methylpyrrolyl, morpholinyl, pyridyl, pyrazinyl, imidazolyl,pyrimidinyl, and pyridazinyl. The preferred heterocyclic is a 5 or6-membered heterocyclic compound. The especially preferred heterocyclicis furyl, pyridyl, pyrazinyl, imidazolyl, pyrimidinyl, and pyridazinyl.The most preferred heterocyclic is furyl, pyridyl, thiazolyl andthienyl.

The preferred compounds are those wherein n is 1, but di, tri andtetrapeptides are also contemplated to be within the scope of theclaims.

The preferred values of R is aryl lower alkyl, especially benzyl,especially those wherein the phenyl ring thereof is unsubstituted orsubstituted with electron donating groups or electron withdrawinggroups, such as halo (e.g., F).

The preferred R₁ is H or lower alkyl. The most preferred R₁ group ismethyl.

The most preferred electron donating substituents and electronwithdrawing substituents are halo, nitro, alkanoyl, formyl,arylalkanoyl, aryloyl, carboxyl, carbalkoxy, carboxamido, cyano,sulfonyl, sulfoxide, heterocyclic, guanidine, quaternary ammonium, loweralkenyl, lower alkynyl, sulfonium salts, hydroxy, lower alkoxy, loweralkyl, amino, lower alkylamino, di(loweralkyl)amino, amino lower alkyl,mercapto, lower alkylthio, and lower alkyldithio. The term “sulfide”encompasses mercapto, and alkylthio, while the term disulfideencompasses alkyldithio. It is more preferred that the electron donatinggroups and electron withdrawing groups do not contain a cyclic group.The electron donating and electron withdrawing groups may be substitutedon any one of R₁, R₂, R₃, R₄, R₅ or R₆, R₇ or R₈ as defined herein.

The ZY groups representative of R₂ and R₃ include hydroxy, alkoxy, suchas methoxy, ethoxy, aryloxy, such as phenoxy; thioalkoxy, such asthiomethoxy, thioethoxy; thioaryloxy such as thiophenoxy; amino;alkylamino, such as methylamino, ethylamino; arylamino, such as anilino;lower dialkylamino, such as, dimethylamino; trialkyl ammonium salt;hydrazino; alkylhydrazino and arylhydrazino, such as N-methylhydrazino,N-phenylhydrazino, carbalkoxy hydrazino, aralkoxycarbonyl hydrazino,aryloxycarbonyl hydrazino, hydroxylamino, such as N-hydroxylamino(—NH—OH), lower alkoxy amino [(NHOR₁₈) wherein R₁₈ is lower alkyl],N-lower alkylhydroxylamino [(NR₁₈)OH wherein R₁₈ is lower alkyl],N-lower alkyl-O-lower alkylhydroxyamino, i.e., [N(R₁₈)OR₁₉ wherein R₁₈and R₁₉ are independently lower alkyl] and o-hydroxylamino (—O—NH₂);alkylamido such as acetamido; trifluoroacetamido; lower alkoxyamino,(e.g., NH(OCH₃); and heterocyclicamino, such as pyrazoylamino.

The preferred heterocyclic groups representative of R₁ and R₃ aremonocyclic heterocyclic moieties of the formula:

or those corresponding partially or fully saturated form thereof whereinn is 0 or 1; and

-   -   R₅₀ is H or an electron withdrawing group or electron donating        group;    -   A, Z, L and J are independently CH, or a heteroatom selected        from the group consisting of N, O, S; and    -   G is CH, or a heteroatom selected from the group consisting of        N, O and S, but when n is O, G is CH, or a heteroatom selected        from the group consisting of NH, O and S with the proviso that        at most two of A, E, L, J and G are heteroatoms.

When n is O, the above heteroaromatic moiety is a five membered ring,while if n is 1, the heterocyclic moiety is a six membered monocyclicheterocyclic moiety. The preferred heterocyclic moieties are thoseaforementioned heterocyclics which are monocyclic.

Thus, the most preferred monocyclic heterocyclic definition of R₂ and R₃is furyl thienyl, thiazolyl, and pyridyl.

If the ring depicted hereinabove contains a nitrogen ring atom, then theN-oxide forms are also contemplated to be within the scope of theinvention.

When R₂ or R₃ is a heterocyclic of the above formula, it may be bondedto the main chain by a ring carbon atom. When n is O, R₂ or R₃ mayadditionally be bonded to the main chain by a nitrogen ring atom.

Other preferred moieties of R₂ and R₃ are hydrogen, aryl, e.g., phenyl,aryl alkyl, e.g., benzyl and alkyl.

It is to be understood that the preferred groups of R₂ and R₃ may beunsubstituted or substituted with electron donating or electronwithdrawing groups. It is preferred that the electron withdrawing groupor electron donating group does not contain a cyclic group, unless theelectron withdrawing group or electron donating group is a hydrocarbylgroup that contains only carbon and hydrogen atoms.

It is more preferred that R₂ and R₃ are independently hydrogen, loweralkyl, which is either unsubstituted or substituted with an electronwithdrawing group or an electron donating group, such as lower alkoxy(e.g., methoxy, ethoxy, and the like), N-hydroxylamino, N-loweralkylhydroxyamino, N-loweralkyl-o-loweralkyl and alkylhydroxyamino.

It is even more preferred that one of R₂ and R₃ is hydrogen; while theother is one of the preferred group indicated hereinabove.

It is preferred that n is one.

It is preferred that R₂ is hydrogen and R₃ is hydrogen, an alkyl groupwhich is unsubstituted or substituted by at least an electron donatingor electron withdrawing group or ZY. In this preferred embodiment, it ismore preferred that R₃ is hydrogen or an alkyl group such as methyl,which is unsubstituted or substituted by an electron donating group,NR₄OR₅ or ONR₄R₇, wherein R₄, R₅ and R₇ are independently hydrogen orlower alkyl. It is preferred that the electron donating group is loweralkoxy, and especially methoxy or ethoxy.

It is also preferred that R is aryl lower alkyl. The most preferred arylfor R is phenyl. The most preferred R group is benzyl. In a preferredembodiment, the aryl group may be unsubstituted or substituted with anelectron donating or electron withdrawing group. If the aryl ring in Ris substituted, it is most preferred that it is substituted with anelectron withdrawing group, especially on the aryl ring. The mostpreferred electron withdrawing group for R is halo, especially fluoro.

The preferred R₁ is loweralkyl, especially methyl.

The more preferred compounds are compounds of formula I wherein n is 1;R₂ is hydrogen; R₃ is hydrogen, an alkyl group, especially methyl whichis substituted by an electron donating or electron withdrawing group orZY; R is aryl, aryl lower alkyl, such as benzyl, wherein the aryl groupis unsubstituted or substituted and R₁ is lower alkyl. In thisembodiment, it is most preferred that R₃ is hydrogen, an alkyl group,especially methyl, substituted by electron donating group, such as loweralkoxy, (e.g., methoxy, ethoxy and the like), NR₄OR₅ or ONR₄R₇ whereinthese groups are defined hereinabove.

The most preferred compounds utilized are those of the formula:

wherein

-   -   Ar is aryl, especially phenyl, which is unsubstituted or        substituted with at least one electron donating group or        electron withdrawing group;    -   R₁ is lower alkyl; and    -   R₃ is as defined herein, but especially hydrogen, loweralkyl,        which is unsubstituted or substituted by at least an electron        donating group or electron withdrawing group or ZY. It is even        more preferred that R₃ is, in this embodiment, hydrogen, an        alkyl group which is unsubstituted or substituted by an electron        donating group, such as alkoxy, or NR₄OR₅ or ONR₄R₇. It is most        preferred that R₃ is CH₂—Q, wherein Q is lower alkoxy, NR₄OR₅ or        ONR₄R₇ wherein R₄ is hydrogen or alkyl containing 1–3 carbon        atoms, R₅ is hydrogen or alkyl containing 1–3 carbon atoms, and        R₇ is hydrogen or alkyl containing 1–3 carbon atoms.

The preferred R₁ is CH₃.

The most preferred aryl is phenyl.

The most preferred compounds include:

(R)-N-Benzyl-2-acetamido-3-methoxypropionamide

O-methyl-N-acetyl-D-serine-m-fluorobenzylamide

O-methyl-N-acetyl-D-serine-p-fluorobenzylamide

N-acetyl-D-phenylglycinebenzylamide

D-1,2-(N,O-dimethylhydroxylamino)-2-acetamide acetic acid benzylamide

D-1,2-(O-methylhydroxylamino)-2-acetamido acetic acid benzylamide

Some of the preferred compounds are described in U.S. Pat. No.5,773,475, the contents of which are incorporated by reference.

It is to be understood that the various combinations and permutations ofthe Markush groups of R₁, R₂, R₃, R and n described herein arecontemplated- to be within the scope of the present invention. Moreover,the present invention also encompasses compounds and compositions whichcontain one or more elements of each of the various Markush groupings inR₁, R₂, R₃, n and R and the various combinations thereof. Thus, forexample, the present invention contemplates that R₁ may be one or moreof the substituents listed hereinabove in combination with any and allof the substituents of R₂, R₃, and R with respect to each value of n.

The compounds utilized in the present invention may contain one (1) ormore asymmetric carbons and may exist in racemic and optically activeforms. The configuration around each asymmetric carbon can be either theD or L form. (It is well known in the art that the configuration aroundchiral carbon atoms can also be described as R or S in theCahn-Prelog-Ingold nomenclature system). All of the variousconfigurations around each asymmetric carbon, including the variousenantiomers and diastereomers as well as racemic mixtures and mixturesof enantiomers, diastereomers or both are contemplated by the presentinvention.

In the principal chain, there exists asymmetry at the carbon atom towhich the groups R₂ and R₃ are attached. When n is 1, the compounds ofthe present invention are of the formula

wherein R, R₁, R₂, R₃, R₄, R₅, R₆, Z and Y are as defined previously.

As used herein, the term configuration shall refer to the configurationaround the carbon atom to which R₂ and R₃ are attached, even thoughother chiral centers may be present in the molecule. Therefore, whenreferring to a particular configuration, such as D or L, it is to beunderstood to mean the D or L stereoisomer at the carbon-atom to whichR₂ and R₃ are attached. However, it also includes all possibleenantiomers and diastereomers at other chiral centers, if any, presentin the compound.

The compounds of the present invention are directed to all the opticalisomers, i.e., the compounds of the present invention are either theL-stereoisomer or the D-stereoisomer (at the carbon atom to which R₂ andR₃ are attached). These stereoisomers may be found in mixtures of the Land D stereoisomer, e.g., racemic mixtures. The D stereoisomer ispreferred.

Depending upon the substituents, the present compounds may form additionsalts as well. All of these forms are contemplated to be within thescope of this invention, including mixtures of the stereoisomeric forms.

The following three schemes of preparation are generally exemplary ofthe process of which can be employed for the preparation of thecompounds utilized. These are described in U.S. Pat. Nos. 5,378,729 and5,773,475, the contents of both of which are incorporated by reference.

wherein R₁, R₂, R₃ and are as defined hereinabove and R₁₇ is loweralkyl, aryl or lower arylalkyl.

More specifically, these compounds can be prepared by art-recognizedprocedures from known compounds or readily preparable intermediates. Forinstance, compounds of Formula I can be prepared by reacting amines ofFormula II with an acylating derivative of a carboxylic acid of FormulaIII under amide forming conditions:

wherein R, R₁, R₂, R₃ and n are as defined hereinabove, although it ispreferred that n is 1.

The amide forming conditions referred to herein involve the use of knownderivatives of the described acids, such as the acyl halides, (e.g.

wherein X is Cl, Br and the like), anhydrides (e.g.,

mixed anhydrides, or lower alkyl esters, and the like. It is preferredthat the acylating derivative used is the anhydride. When alkyl estersare employed, amide bond formation can be effected by metal cyanidessuch as sodium or potassium cyanides.

Another exemplary procedure for preparing compounds wherein at least oneof R₂ and R₃ is aromatic or heteroaromatic is depicted in Scheme IV.

The ester (IV) is reacted with halogen and ultraviolet light in thepresence of a catalyst, e.g., AIBN, to form the halo derivative (V). (V)is reacted in the presence of a Lewis acid, such as zinc chloride, withan aromatic or heteroaromatic compound to form the compound (VI). (VI)in turn is hydrolyzed and then reacted with alkylhaolformate, such asalkylchloroformate, in the presence of a tertiary amine to generate themixed N-acyl amino acid carbonic ester anhydride (VIII). Thisintermediate is reacted with an amine under amide forming conditions togive the compound of Formula I. Alternatively, (VI) can be reacteddirectly with an amine (RNH₂), optionally in the presence of a metalcatalyst, such as metal cyanides, e.g., potassium or sodium cyanide,under amide forming conditions to form a compound of Formula I.Alternatively, compound VIII can be prepared by an independent methodand converted to VI which is then reacted with an amine, with or withoutcatalyst, to form the compound of Formula I.

wherein X=halogen (i.e., Cl, Br);

-   -   R₁₇=lower alkyl, aryl, or aryl lower alkyl; and    -   M+=metal cation (i.e., Na⁺, K⁺)

Two additional synthetic routes may be employed for the preparation ofcompounds wherein R₂ or R₃ is Z—Y as defined hereinabove. In one scheme,for the preparation of these complexes, a substitution reaction is used:

In the above scheme, R₉ is lower alkyl, R₂ is Z—Y and Z, Y, R, R₃ and R₁are as defined hereinabove and M is a metal.

The ether functionality on IX can be cleaved by treatment with Lewisacids, such as BBr₃, in an inert solvent such as methylene chloride toform the corresponding halo (bromo) derivative. Addition of either anexcess of H—R₂ or MR₂ or the sequential addition of triethylamine andH—R₂ to a THF mixture containing the halo derivative furnishes thedesired product. For example, in the case wherein the compound ofFormula IX is 2-acetamido-N-benzyl-2-ethoxy acetamide, its treatmentwith BBr₂ in CH₂Cl₂ led to the formation of the α-bromo derivative,2-acetamido-N-benzyl-2-bromoacetamide. Addition of an excess of HR₂ orthe sequential addition of triethylamine and HR₂ to the THF mixturecontaining the bromo adduct furnishes the desired product.

In another procedure, the product wherein R₂ or R₃ is Z—Y can also beprepared by a substitution reaction on a quaternary ammonium derivativeof the compound of Formula I as outlined below:

In scheme VI, R, R₁, R₃ and R are as defined hereinabove, R₂ is Z—Y andR₉ and R₁₀ are independently lower alkyl. In scheme VI, methylation ofcompound X with a methylation reagent, such as trimethyloxoniumtetrafluoroborate, provided the corresponding ammonium derivative.Subsequent treatment of the ammonium salt with HR₂ furnishes the desiredproduct. For example, methylation of2-acetamido-N-benzyl-2-(N,N-dimethylamino) acetamide withtrimethyloxonium tetrafluoroborate in nitromethane furnished thequaternary ammonium derivative,2-acetamido-N-benzyl-(N,N,N-trimethylammonium) acetamidetetrafluoroborate in high yields. Subsequent treatment of the salt withthe HR₂ reagent in the methanol leads to the production of the desiredproduct.

As in any organic reaction, inert solvents can be employed such asmethanol, ethanol, propanol, acetone, tetrahydrofuran, dioxane,dimethylformamide, dichloromethane, chloroform and the like. Thereaction is normally effected at or near room temperature, althoughtemperatures from 0° C. up to the reflux temperature of the solvent canbe employed.

As a further convenience, the amide forming reaction can be effected inthe presence of a base, such as a tertiary organic amine, e.g.,triethylamine, pyridine, 4-methyl-morpholine, picolines and the like,particularly where hydrogen halide is formed by the amide formingreaction, e.g., the reaction of an acyl halide and the amine of FormulaII. Of course, in those reactions where hydrogen halide is produced, anyof the commonly used hydrogen halide acceptors can also be used.

The exact mineral acid or Lewis acid employed in the reaction will varydepending on the given transformation, the temperature required for theconversion and the sensitivity of the reagent toward the acid in thereaction mixture.

The various substituents, e.g., as defined in R, R₁, R₂, and R₃, can bepresent in the starting compounds, added to any one of the intermediatesor added after formation of the final products by the known methods ofsubstitution or conversion reactions. For example, the nitro groups canbe added to the aromatic ring by nitration and the nitro group convertedto other groups, such as amino by reduction, and halo by diazotizationof the amino group and replacement of the diazo group. Alkanoyl groupscan be substituted onto the aryl groups by Friedel-Crafts acylation. Theacyl groups can be then transformed to the corresponding alkyl groups byvarious methods, including the Woff-Kishner reduction or Clemmensonreduction. Amino groups can be alkylated to form mono, dialkylamino andtrialkylamino groups; and mercapto and hydroxy groups can be alkylatedto form corresponding thioethers or ethers, respectively. Primaryalcohols can be oxidized by oxidizing agents known in the art to formcarboxylic acids or aldehydes, and secondary alcohols can be oxidized toform ketones. Thus, substitution or oxidation reactions or a combinationthereof can be employed to provide a variety of substituents throughoutthe molecule of the starting material, intermidiates, or the finalproduct.

In the above reactions, if the substituents themselves are reactive,then the substituents can themselves be protected according totechniques known in the art. A variety of protecting groups known in theart may be employed. Examples of many of these possible groups may befound in “Protective Groups in Organic Synthesis,” by T. W. Greene, JohnWiley & Sons, 1981.

Resulting mixtures of isomers can be separated into the pure isomers bymethods known to one skilled in the art, e.g., by fractionaldistillation, crystallization and/or chromatography.

The compounds obviously exist in stereoisomeric forms and the productsobtained thus can be mixtures of the isomers, which can be resolved.Optically pure functionalized amino acid derivatives can be prepareddirectly from the corresponding pure chiral intermediate. Racemicproducts can likewise be resolved into the optical antipodes, forexample, by separation of diastereomeric salts thereof, e.g., byfractional crystallization, by selective enzymatic hydrolysis, e.g.,papain digestion, or by use of a chiral stationary phase in achromatographic separation, such as by high pressure liquidchromatography (HPLC). For a discussion of chiral stationary phases forHPLC, See, DeCamp, Chirality, 1, 2–6 (1989), which is incorporatedherein by reference with the same force and effect as is fully set forthherein.

For example, a racemic mixture of an intermediate in any of the schemesdepicted hereinabove has the formula:

wherein R₁₇ is H (which can be prepared according to the procedures ofSchemes 1, 2, 3 or 4) is reacted with an optically active amine, RNH₂,e.g., (R)(+)α-methylbenzylamine, to form a pair of diastereomeric salts.Diastereomers can then be separated by recognized techniques known inthe art, such as fractional recrystallization and the like.

In another method, a racemic mixture of final products or intermediatescan be resolved by using enzymatic methods. Since enzymes are chiralmolecules, it can be used to separate the racemic modification, since itwill preferentially act on one of the compounds, without affecting theenantiomer. For example, acylase, such as acylase I, can be used toseparate the racemic modification of an intermediate D, L(±)α-acetamido-2-furanacetic acid. It acts on theL(±)α-acetamido-2-furanacetic acid, but will not act on the Denantiomer. In this way, the D(−)α-acetamido-2-furanacetic acid can beisolated. The intermediate can then react with the amine (RNH₂) underamide forming conditions as described hereinabove to form the compoundof Formula I.

The compounds utilized in the present invention are useful as such asdepicted in the Formula I or can be employed in the form of salts inview of its basic nature by the presence of the free amino group. Thus,the compounds of Formula I form salts with a wide variety of acids,inorganic and organic, including pharmaceutically acceptable acids. Thesalts with therapeutically acceptable acids are of course useful in thepreparation of formulations where enhanced water solubility is mostadvantageous.

These pharmaceutically acceptable salts have also therapeutic efficacy.These salts include salts of inorganic acids such as hydrochloric,hydroiodic, hydrobromic, phosphoric, metaphosphoric, nitric acid andsulfuric acids as well as salts of organic acids, such as tartaric,acetic, citric, malic, benzoic, perchloric, glycolic, gluconic,succinic, aryl sulfonic, (e.g., p-toluene sulfonic acids,benzenesulfonic), phosphoric, malonic, and the like.

It is preferred that the compound utilized in the present invention isused in therapeutically effective amounts.

The physician will determine the dosage of the present therapeuticagents which will be most suitable and it will vary with the form ofadministration and the particular compound chosen, and furthermore, itwill vary with the patient under treatment, the age of the patient, andthe type of malady being treated. He will generally wish to initiatetreatment with small dosages substantially less than the optimum dose ofthe compound and increase the dosage by small increments until theoptimum effect under the circumstances is reached. The compounds areuseful in the same manner as comparable therapeutic agents and thedosage level is of the same order of magnitude as is generally employedwith these other therapeutic agents.

In a preferred embodiment, the compounds utilized are administered inamounts ranging from about 1 mg to about 100 mg per kilogram of bodyweight per day. This dosage regimen may be adjusted by the physician toprovide the optimum therapeutic response. For example, several divideddoses may be administered daily or the dose may be proportionallyreduced as indicated by the exigencies of the therapeutic situation. Thecompounds of Formula I may be administered in a convenient manner, suchas by oral, intravenous (where water soluble), intramuscular orsubcutaneous routes.

The compounds of Formula I may be orally administered, for example, withan inert diluent or with an assimilable edible carrier, or it may beenclosed in hard or soft shell gelatin capsules, or it may be compressedinto tablets, or it may be incorporated directly into the food of thediet. For oral therapeutic administration, the active compound ofFormula I may be incorporated with excipients and used in the form ofingestible tablets, buccal tablets, troches, capsules, elixirs,suspensions, syrups, wafers, and the like. Such compositions andpreparations should contain at least 1% of active compound of Formula I.The percentage of the compositions and preparations may, of course, bevaried and may conveniently be between about 5 to about 80% of theweight of the unit. The amount of active compound of Formula I in suchtherapeutically useful compositions is such that a suitable dosage willbe obtained. Preferred compositions or preparations according to thepresent invention contains between about 10 mg and 6 g of activecompound of Formula I.

The tablets, troches, pills, capsules and the like may also contain thefollowing: a binder such as gum tragacanth, acacia, corn starch orgelatin; excipients such as dicalcium phosphate; a disintegrating agentsuch as corn starch, potato starch, alginic acid and the like; alubricant such as magnesium stearate; and a sweetening agent such assucrose, lactose or saccharin may be added or a flavoring agent such aspeppermint, oil of wintergreen, or cherry flavoring. When the dosageunit form is a capsule, it may contain, in addition to materials of theabove type, a liquid carrier.

Various other materials may be present as coatings or otherwise modifythe physical form of the dosage unit. For instance, tablets, pills, orcapsules may be coated with shellac, sugar or both. A syrup or elixirmay contain the active compound, sucrose as a sweetening agent, methyland propylparabens as preservatives, a dye and flavoring such as cherryor orange flavor. Of course, any material used in preparing any dosageunit form should be pharmaceutically pure and substantially non-toxic inthe amounts employed. In addition, the active compound may beincorporated into sustained-release preparations and formulations. Forexample, sustained release dosage forms are contemplated wherein theactive ingredient is bound to an ion exchange resin which, optionally,can be coated with a diffusion barrier coating to modify the releaseproperties of the resin.

The active compound may also be administered parenterally orintraperitoneally. Dispersions can also be prepared in glycerol, liquidpolyethylene glycols, and mixtures thereof, and in oils. Under ordinaryconditions of storage and use, these preparations contain a preservativeto prevent the growth of microorganisms.

The pharmaceutical forms suitable for injectable use include sterileaqueous solutions (where water soluble) or dispersions and sterilepowders for the extemporaneous preparation of sterile injectablesolutions or dispersions. In all cases, the form must be sterile andmust be fluid to the extent that easy syringability exists. It must bestable under the conditions of manufacture and storage and must bepreserved against the contaminating action of microorganisms such asbacteria and fungi. The carrier can be a solvent or dispersion mediumcontaining, for example, water, ethanol, polyol (for example, glycerol,propylene glycol, and liquid polyethylene glycol, and the like),suitable mixtures thereof, and vegetable oils. The proper fluidity canbe maintained, for example, by the use of a coating such as lecithin, bythe maintenance of the required particle size, in the case ofdispersions, and by the use of surfactants. The prevention of the actionof microorganisms can be brought about by various antibacterial andantifungal agents, for example, parabens, chlorobutanol, phenol, sorbicacid, thimerosal, and the like. In many cases, it will be preferable toinclude isotonic agents, for example, sugars or sodium chloride.Prolonged absorption of the injectable compositions can be brought aboutby the use in the compositions of agents delaying absorption, forexample, aluminum monostearate and gelatin.

Sterile injectable solutions are prepared by incorporating the activecompound in the required amount in the appropriate solvent with variousother ingredients enumerated above, as required, followed by filteredsterilization. Generally, dispersions are prepared by incorporating thevarious sterilized active ingredients into a sterile vehicle whichcontains the basic dispersion medium and the required other ingredientsfrom those enumerated above. In the case of sterile powders for thepreparation of sterile injectable solutions, the preferred methods ofpreparation are the use of vacuum drying and freeze-drying techniques onthe active ingredient plus any additional desired ingredients frompreviously sterile-filtered solution(s) thereof.

As used herein, “pharmaceutically acceptable carrier” includes any andall solvents, dispersion media, coatings, antibacterial and antifungalagents, isotonic and absorption delaying agents for pharmaceuticalactive substances which are well known in the art. Except insofar as anyconventional media or agent is incompatible with the active ingredient,its use in the therapeutic compositions is contemplated.Supplementary-active ingredients can also be incorporated into thecompositions.

It is especially advantageous to formulate parenteral compositions indosage unit form for ease of administration and uniformity of dosage.Dosage unit form as used herein refers to physically discrete unitssuited as unitary dosages for the mammalian subjects to be treated; eachunit containing a predetermined quantity of active material calculatedto produce the desired therapeutic effect in association with therequired pharmaceutical carrier. The specifics for the novel dosage unitforms of the invention are dictated by and directly dependent on (a) theunique characteristics of the active material and the particulartherapeutic effect to be achieved, and (b) the limitations inherent inthe art of compounding such as active material for the treatment ofdisease in living subjects having a diseased condition in which bodilyhealth is impaired as herein disclosed in detail.

The principal active ingredient is compounded for convenient andeffective administration in effective amounts with a suitablepharmaceutically acceptable carrier in dosage unit form as hereinbeforedescribed. A unit dosage can, for example, contain the principal activecompound in amounts ranging from about 10 mg to about 6 g. Expressed inproportions, the active compound is generally present from about 1 toabout 750 mg/ml of carrier. In the case of compositions containingsupplementary active ingredients, the dosages are determined byreference to the usual dose and manner of administration of the saidingredients.

As used herein the term “patient” or “subject” refers to a warm bloodedanimal, preferably mammals, such as, for example, cats, dogs, horses,cows, pigs, mice, rats and primates, including humans. The preferredpatient is human.

The term “treat” refers to either relieving the pain associated with adisease or condition or alleviating the patient's disease or condition.

The compounds of the present invention are useful for treating chronicpain. As used herein, the term “chronic pain” is defined as painpersisting for an extended period of time, for example, greater thanthree to six months, although the characteristic signs describedhereinbelow can occur earlier or later than this period. Vegetativesigns, such as lassitude, sleep disturbances, decreased appetite, lossof taste or food, weight loss, diminished libido and constipationdevelop.

A type of chronic pain that the compounds of the present invention areespecially useful in treating is nociceptive pain and neuropathic pain.As used herein, “nociceptive pain” is pain that is judged to becommensurate with on-going activation of pain-sensitive somatic orvisceral nerve fibers. This pain is typically experienced as aching orpressure-like when somatic nerves are involved.

On the other hand, neuropathic pain is caused by damage to nerve tissue.The pain may result from nervous system damage involving reorganizationof central somato-sensory processing, i.e., differentiation pains (thosedue to partial or complete interruption of peripheral or centralafferent neural activity) and those dependent on sympathetic-mediatedpains (those dependent on efferent sympathetic activity). Alternatively,the pain may result from on-going peripheral processes or pathology,such as nerve compression or neuroma formation.

The pain associated with these neuropathic pains is a deep pain, i.e., aspontaneous burning pain often accompanied by a superimposed-lancinatingcomponent. Other pain sensations, such as hyperesthesia, hyperalgesia,allodynia (pain from a non-noxious stimulant) and hyperpathia(particularly unpleasant, exaggerated pain response) may also be felt bythe patient experiencing neuropathic pain.

The compounds of the present invention are administered to a patientsuffering from neuropathic pain in an analgesic effective amount. Theseamounts are equivalent to the therapeutically effective amountsdescribed hereinabove.

Another type of malady experienced by patients for which the compoundsof Formula I are useful in treating is headaches, especially migraineheadaches.

A migraine headache is a paroxysmal disorder characterized by recurrentattacks of headaches, which may be associated with visual or GIdisturbances. In migraine headaches, the pain is usually generalized,but it may also be a unilateral throbbing, which begins around one ofthe eyes and then spreads through the head to involve one or both sides.

In some severe cases, it is accompanied by anorexia, nausea and vomitingand photophobia. In addition, the extremities are cold and cyanosed, andthe patient is irritable. Moreover, the scalp arteries are prominent andtheir amplitude of pulsation is increased.

The compounds of Formula I are useful in the prophylaxis and thetreatment of migraine headaches and alleviating the pain associatedtherewith. They are administered to patients with migraine headaches inpain relieving effective amounts. These amounts are equivalent to thetherapeutically effective amounts described hereinabove. The discussionsassociated with therapeutic effective amounts are applicable to thetreatment and/or prophylaxis of migraine headaches and are incorporatedherein.

The compounds of the present invention are also useful in treatingpatients with bipolar disorders. Bipolar disorders commonly originatewith depression and are characterized by at least one elated periodduring the course of the illness. In bipolar I disorder, majordepressive episodes and full-blown manic alternate. In bipolar IIdisorder, depressive episodes alternate with hypomanias (i.e., mild,non-psychotic periods of excitement) of relatively short duration. Thesedisorders are typically accompanied by the subject experiencinghypersomnia and overeating and these traits may recur on a seasonalbasis. Additionally, the patient may suffer from insomnia and poorappetite.

In the full blown bipolar disorder, the mood of the person sufferingtherefrom is usually elation, but irritability and frank hostility andcantankerousness are also common. The patient is morbid, yet the patientbelieves that he is in the best mental state. He is psychotic,impatient, intrusive, meddlesome and responds with aggressiveirritability when challenged or crossed. The patient may experienceinterpersonal friction and he may have secondary paranoid delusionalinterpretations of being persecuted. The patient usually suffers fromdelusions, especially grand delusions, e.g., false belief of personalwealth, power, inventiveness, genius or importance. The patient maybelieve that he is being assaulted or persecuted by others. He may evensuffer from hallucinations. In the extreme, the psychomotor activity isso frenzied that any understandable link between mood and behavior islost (delirious mania).

The present compounds are also useful for treating cyclothymicdisorders.

The term bipolar disorders, as used herein, also includes mixed stateswhich are rapid alternation between depression and manic manifestations,as for example, momentary switching into tearfulness and suicidal ideas.

The amounts effective for treating bipolar disorders are thetherapeutically effective amounts described hereinabove. The discussionsassociated with therapeutic effective amounts are applicable to thetreatment of bipolar disorders and are incorporated herein by reference.

The compounds of the present invention are useful in treating varioustypes of neuroses, especially obsessive-compulsive neurosis.

The former, by definition, is a disorder characterized by the presenceof ideas and fantasies which are recurrent, in fact obsessive and byrepetitive impulses or actions (compulsions) that the patient recognizesas morbid and toward which he feels a strong inner resistance. Thepatient himself is anxious, but the anxiety arises in response tointernally derived thoughts and disorders that the patient fears he mayexecute despite a desire to restrain himself.

Again, the amounts described herein are therapeutically effectiveamounts, which discussions are incorporated herein by reference.

Without wishing to be bound, the compounds of the present invention arebelieved to interact with the strychnine-insensitive glycine site of theNMDA receptor. By “interact”, it is meant that the compounds may be NMDAantagonists, NMDA agonists or partial agonists/antagonists.

The NMDA (N-methyl-D-aspartate) receptor is one of the three majorsub-types of glutamate receptors in the CNS Glutamate, which is believedto be the major excitatory neurotransmitter in the brain, activates theNMDA receptor. The NMDA receptors are found in the membranes ofvirtually every neuron in the brain. NMDA receptors are ligand gatedcation channels that allow Na⁺, K⁺, and Ca⁺² to permeate when they areactivated by glutamate, aspartate or NMDA.

However, glutamate alone cannot activate the NMDA receptor. In order tobecome fully activated by glutamate, the NMDA receptor channel must bindglycine at a specific, high affinity glycine binding site that isseparate from the glutamate/NMDA binding site of the receptor protein.Glycine is therefore an obligatory co-agonist at the NMDAreceptor/channel complex.

In addition to the binding site for glutamate/NMDA and glycine, the NMDAreceptor carries a number of other functionally important binding sites,e.g., Mg²⁺; Zn²⁺, polyamines, arachidonic acid and phencyclidine (PCP).

Without wishing to be bound, it is thus believed that functionalmodulation of the NMDA subclass of glutamate receptors can be achievedthrough actions at different recognition sites such as: the primarytransmitter site (competitive), the phencyclidine (PCP) site locatedinside the cation channel (uncompetitive), the polyamine modulatorysite, and the strychnine-insensitive glycine site (glycine_(b)).

Without wishing to be bound, it is believed that the compounds of thepresent invention interact with the glycine binding site of the NMDAreceptor. For example, the compounds of the present invention may beantagonists of the glycine binding site of the NMDA receptor.

Glycine is a co-agonist at NMDA receptors and its presence at moderatenM concentrations is a prerequisite for channel activation by glutamateor NMDA. D-serine is also known as an endogenous agonist for theglycine_(b) receptors. In fact, the D-isomers of serine and alanine arenearly as potent as glycine and considerably more potent than theL-isomers; and these also modulate the glycine_(b) site. Larger aminoacids are less effective. Cycloserine shows up as a relatively potentglycine agonist at the NMDA receptor complex site.

Although a number of uncompetitive and competitive NMDA receptorantagonists are already used clinically or are at advanced stages ofdevelopment, less is known about the therapeutic potential ofantagonists at the glycine_(b) site. Initial preclinical evidencesuggests that a different, perhaps more promising, therapeutic profilecan be expected from glycine_(b) antagonism. The glycine_(b) antagonistshave been reported to lack many of the side effects classicallyassociated with NMDA receptor blockade such as: 1) lack ofneurodegenerative changes in the cingulate/retrosplenial cortex; 2) lackof psychotomimetic-like effects, and 3) lack of learning impairingeffects at anticonvulsive doses. However, more recently some fullglycine_(b) antagonists, have also been reported to have goodtherapeutic indices following systemic administration as neuroprotectiveagents in models of focal ischemia; and trauma, as antiepileptics, evenin models of partial complex seizures; as anxiolytics; asantipsychotomimetics; in blocking spreading depression; and in models ofhyperalgesia.

The compounds of the present invention exhibit no specific affinity fora standard battery of CNS and peripheral receptors, including manysubtypes of glutamate receptors. However, they do exhibit affinity atthe glycine strychnine-insensitive site of the NMDA receptor complex.For example, utilizing a representative compound,(R)-2-Acetamido-N-benzyl-3-methoxy propionamide, the present inventorhas determined that the affinity thereof at theglycine-strychnine-insensitive site of the NMDA receptor complex has aIC₅₀ value of 5.3 uM using dichlorokynurenic acid as the ligand.Moreover, other studies have indicated that the proactive effects ofthis representative compound on threshold extension in rats can bereversed by D-serine, a glycine agonist, in a dose dependent fashion.Thus the compounds of the present invention are believed, withoutwishing to be bound, to be mediated by its interaction with theglycine_(b)/D-serine site.

However, the compounds of the present invention exhibit little or noside effects caused by non-selective binding with other receptors,particularly the PCP binding site of the NMDA receptor and the glutamatebinding site of the NMDA receptor.

There is an endogenous ligand present that binds to the glycine_(b)site. Some believe that it is glycine, while others believe that it isD-serine. See Snyder, et al., Am. J. Psychiatry, 2000, 157, 111738–1751; and Baranano, et al., Trends in Nurosciences, 2001, 24,99–106.

Without wishing to be bound, it is believed that the compounds of thepresent invention modulate the activity of the glycine_(b) receptor.Moreover, without wishing to be bound, it is believed that the compoundsof the present invention are useful for the treatment of conditionsassociated with or caused by abnormal receptor activity at theglycine_(b) receptor site. Without wishing to be bound, it is believedthat compounds of the present invention interact with this glycine_(b)receptor site on the NMDA receptor.

Without wishing to be bound, it is believed that by interacting at thestrychnine-insensitive glycine site on the NMDA receptors, the compoundsof Formula I are useful in treating or preventing neuronal loss,neurodegenerative diseases and chronic pain. In addition they are alsoanti-psychotics.

Other neurodegenerative diseases which are treated with the compounds ofFormula I are Alzheimer's disease, Huntington's disease and Down'ssyndrome.

The compounds described herein also are useful for treating orpreventing dementia.

Besides treating neuropathic pain, the compounds of the presentinvention find utility in treating or preventing pain, e.g., chronicpain. Such chronic pain can result from surgery, trauma, headache,arthritis, pain associated with a terminal case of cancer, ordegenerative diseases. The compounds of Formula I find utility in thetreatment of phantom pain that results from amputation of an extremity.

In addition, it is believed, without wishing to be bound, that thestrychnine-insensitive glycine site of the NMDA receptors is involved inthe development of persistent pain following nerve and tissue injury.Tissue injury, such as that caused by injecting a small amount offormalin subcutaneously into the hindpaw of a test animal, has beenshown to produce an immediate increase of glutamate and aspartate in thespinal cord. Without wishing to be bound, it is believed that theadministration of the compounds of the present invention reduces theresponse of spinal cord dorsal horn neurons following formalininjection. These dorsal horn neurons are critical in carrying the painsignal from the spinal cord to the brain and a reduced response of theseneurons is indicative of a reduction in pain perceived by the testanimal to which pain has been inflicted by subcutaneous formalininjection.

Because the compounds of the present intention block dorsal horn neuronresponse induced by subcutaneous formalin injection, they are useful forthe treatment of chronic pain, such as pain caused by surgery or byamputation (phantom pain) or by infliction of other wounds (wound pain).

The degree of pain is determined by measuring the decrease in the amountof time the animal spends licking the formalin-injected paw afteradministration of the drug.

Compared to vehicle control, the intraperitoneal injection of theputative glycine receptor modulators of the present invention 30 minutesprior to formalin injection into the hindpaw significantly inhibitsformalin-induced chronic pain in a dose-dependent manner as determinedby the reduction of the time spent by the mouse licking the formalininjected hindpaw. This is shown in Example 2 hereinbelow.

In the following Examples 1–5, the following were used:

1. Animals

Male or female ICR mice and male or female Long Evans rats provided byanimal breeding center of MDS Panlabs Taiwan, Ltd. were used. Spaceallocation for animals was as follows: 45×23×15 cm for 10 mice, 45×23×15cm for 6 rats. Mice and rats were housed in APEC® (Allentown Gaging,Allentown, N.J. 08501, U.S.A.) cages in a positive pressure isolator(NuAire®, Mode: Nu-605, airflow velocity 50±5 ft/min, HEPA Filter). Allanimals were maintained in a controlled temperature (22° C.–24° C.) andhumidity (60%–80%) environment with 12 hour light dark cycles for atleast one week in MDS Panlabs Taiwan laboratory prior to being used.Free access to standard lab chow for mice and rats (Fwusow Industry Co.,Limited, Taiwan) and tap water was granted. All aspects of this workincluding housing, experimentation and disposal of animals wereperformed in general accordance with the International GuidingPrinciples for Biomedical Research Involving Animals (CIOMS PublicationNo. ISBN 90360194, 1985).

2. Chemicals

The chemicals used were Acetic Acid (Sigma, U.S.A.), Aspirin (ICNBiomedicals Inc.), CGS-19755 (RBI, U.S.A.), Diazepam (Sigma, U.S.A.),Formalin (Wako, Japan), Morphine (National Narcotics Bureau of Taiwan),NMDA (Sigma, U.S.A.), Phenylquionone (Sigma, U.S.A.) and Saline (Astar,Taiwan).

3. (R)-N-Benzyl-3-Acetamido-3-methoxypropionamide was prepared inaccordance with the procedure in U.S. Pat. No. 5,773,475. In thefollowing examples, it will be designated as Compound I.

The following experiments illustrate the effectiveness of the compoundsin treating pain. In the first series of experiments, a representativecompound of the present invention,(R)-2-Acetamido-N-benzyl-3-methoxypropionamide (CMPD I) was utilized atdifferent concentrations.

In the first animal study in Example 1, the degree of pain experiencedby the mice after injection by acetic acid is seen by the number ofwrithes. If the mice experience no pain, there is no writhing. As wouldbe expected, if a pain reliever is not administered to the mice prior toinjection of acetic acid, the mice will exhibit writhing.

The protocol is based on the acetic acid writhing test in mice,developed by R. Koster, et al. Fed. Proc, 18, 412 (1939), and referredto a Koster test and Hunskarai, S., et al., J. Neuroscience Meth. 14:69–76, 1985.

EXAMPLE 1

Test substance was administered PO (30 or 100 mg/kg) to groups of 3 ICRderived male or female mice weighing 22±2 gms one hour before injectionof acetic acid (0.5%, 20 ml/kg IP). Reduction in the number of writhesby 50 percent or more (≧50%) per group of animals observed during the 5to 10 minute period after acetic acid administration, relative to avehicle treated control group, indicated analgesic activity.

The results are tabulated hereinbelow:

TABLE 1 Protocol #50390 Analgesia, Acetic Acid Writhing % Inh. CompoundRoute Dose No. No. of Writhes Distilled PO 20 ml/kg 1 17 0 water PO 20ml/kg 2 12 Distilled PO 20 ml/kg 3 18 water Distilled water x ± SEM 15.7± 1.9 Compound I PO 100 mg/kg 1 0 100 Compound I PO 100 mg/kg 2 0Compound I PO 100 mg/kg 3 0 x ± SEM 0 ± 0 Compound I PO 30 mg/kg 1 18 4Compound I PO 30 mg/kg 2 12 Compound I PO 30 mg/kg 3 15 x ± SEM 15 ± 1.7Aspirin PO 100 mg/kg 1 0 100 Aspirin PO 100 mg/kg 2 0 Aspirin PO 100mg/kg 3 0 x ± SEM 0 ± 0 Note: Compound I, at a dose of 100 mg/kg, 3 outof 3 animals showed slight convulsions 15 minutes after oraladministration.

As clearly shown, the administration of compound I at 100 mg/Kg waseffective in reducing pain, as indicated by the number of writhes. Infact, when compound I was administered at 100 mg/Kg, the miceexperienced no writhes after acetic acid administration. The same resultwas seen with aspirin, a known analgesic.

This next experiment shows that the compounds of the present inventionare also effective in reducing pain resulting from tissue injury, suchas that caused by injecting a small amount of formalin subcutaneouslyinto the hindpaw of a mouse.

EXAMPLE 2

Test substance was administered (30 or 100 mg/kg) to groups of 5 ICRderived male or female mice weighing 22±2 gms one hour before subplantarinjection of formalin (0.02 ml, 5%). Reduction of the induced hind pawlicking time recorded during the following 20 to 30 minutes period by 50percent or more (≧50%) indicated analgesic activity.

The results are tabulated hereinbelow:

TABLE 2 Licking Time (sec.) Compound Route Dose N Indiv. Ave. % Inh.Distilled water PO 20 ml/kg 1 146 128 0 Distilled water PO 20 ml/kg 2150 Distilled water PO 20 ml/kg 3 121 Distilled water PO 20 ml/kg 4 134Distilled water PO 20 ml/kg 5 88 Compound I PO 100 mg/kg 1 0 0 100Compound I PO 100 mg/kg 2 0 Compound I PO 100 mg/kg 3 0 Compound I PO100 mg/kg 4 0 Compound I PO 100 mg/kg 5 0 Compound I PO 30 mg/kg 1 122100 22 Compound I PO 30 mg/kg 2 125 Compound I PO 30 mg/kg 3 62 CompoundI PO 30 mg/kg 4 127 Compound I PO 30 mg/kg 5 63 Aspirin PO 300 mg/kg 130 36 72 Aspirin PO 300 mg/kg 2 36 Aspirin PO 300 mg/kg 3 51 Aspirin PO300 mg/kg 4 9 Aspirin PO 300 mg/kg 5 54 Note: Compound I, at a dose of100 mg/kg, 5 out of 5 animals showed slight convulsions at 15 minutesafter oral administration.

The results clearly show that at 100 mg/Kg, there was less licking bythe mice than when aspirin was administered at 300 mg/Kg. Therefore,this shows that the compounds of the present invention are moreeffective than aspirin in reducing pain from tissue damages.

The following example illustrates that the compounds of the presentinvention are not antagonists of the opioid receptor.

EXAMPLE 3

Groups of 4 male ICR mice weighing 22±2 gms were employed. A dose (30mg/kg) of test compound dissolved in a vehicle of saline wasadministered intraperitoneally. The control group received vehiclealone. At pretreatment (0 minute) a focused beam of radiant heat wasapplied to the middle dorsal surface of the tail to elicit a tail flickresponse within 6–7.5 seconds in pre-treated animals. A maximum cut-offtime of 15 seconds was set. The time required to elicit a pain responsewas recorded for each animal at 0 and 30 minutes followingadministration of test compound. Prolongation by 50 percent or more(≧50%) of the time required to elicit a tail flick indicated analgesicactivity.

The results are as indicated hereinbelow:

TABLE 3 Response Time Compound Route Dose N 0 Min. 30 Min. % Inh. Saline(Vehicle) IP 20 ml/kg 1 6.2 6.2 0 Saline (Vehicle) IP 20 ml/kg 2 6.6 5.6Saline (Vehicle) IP 20 ml/kg 3 7.0 5.3 Saline (Vehicle) IP 20 ml/kg 46.3 5.7 x 6.5 5.7 SEM 0.2 0.2 Compound I IP 30 mg/kg 1 6.4 5.8 0Compound I IP 30 mg/kg 2 7.3 5.0 Compound I IP 30 mg/kg 3 6.4 6.0Compound I IP 30 mg/kg 4 6.5 6.2 x 6.7 5.8 SEM 0.2 0.3 Morphine IP 10mg/kg 1 7.4 >15 100 Morphine IP 10 mg/kg 2 6.5 >15 Morphine IP 10 mg/kg3 6.4 >15 Morphine IP 10 mg/kg 4 7.4 >15 x 6.9 15.0 SEM 0.3 0.0

The data show that the radiant heat induced tail flick response wasunaffected by administration of the compound at 30 mg/Kg. On the otherhand, morphine gave a positive response. This data show that Compound Idoes not work by the same mechanism as morphine does; i.e., Compound Idoes not function through an opioid receptor.

The compounds of the present invention do not have affinity for theserotonin 5-HT_(1A) receptor as determined by a challenge with the 5HT_(1A) agent, 5-methoxy-N,N-dimethyltryptamine, as shown by thefollowing example.

EXAMPLE 4

Test substance was administered PO (30 mg/kg) to a group of 3 Long Evansderived male or female rats weighing 150±20 gms one hour beforeinjection of 5-MeODMT (5-methoxy-N,N-dimethyltryptamine, 3 mg/kg IP).Each animal exhibiting more than 2 head twitches during the ensuing 1 to5 minute observation period was considered positive. Positive responsesoccurring in 2 or more (≧2) of the 3 animals was considered asignificant effect

The results are tabulated hereinbelow:

TABLE 4 Compound Ave. Route Dose No Head Twitch Distilled PO 10 ml/kg 10 0 water (Vehicle) Distilled PO 10 ml/kg 2 0 water (Vehicle) DistilledPO 10 ml/kg 3 0 water (Vehicle) Compound I PO 30 mg/kg 1 2 1 Compound IPO 30 mg/kg 2 0 Compound I PO 30 mg/kg 3 0 Diazepam PO 10 mg/kg 1 3 2Diazepam PO 10 mg/kg 2 0 Diazepam PO 10 mg/kg 3 2

No potentiation of 5-MeODMT-induced heat twitch was observed utilizing30 mg/Kg of the representative compound PO.

EXAMPLE 5

Test substance was administered ICVT (intracerebroventricular, 30 μg in5 pl/mouse). The appearance of convulsions/mortality in 2 or more (≧2)of 3 ICR derived male or female mice weighing 22±2 gms within the 5minutes thereafter would indicate NMDA receptor agonism. At a dose whereno significant agonist activity was seen within 5 minutes, ability toinhibit NMDA (60 mg/kg IV)-induced Tonic convulsions/mortality in 2 ormore (≧2) of 3 ICR derived male or female mice weighing 22±gms withinthe following 5 minutes indicated NMDA receptor antagonist activity.

The results are tabulated hereinbelow:

TABLE 5 Compound Antagonism Route Conc. N Agonism Vehicle ICVT 5μl/mouse 3 0 0 (Saline) Compound I ICVT 30 μg/mouse 3 0 1 Cis-4- ICVT0.2 μg/mouse 3 0 3 Phosphono- methyl-2- piperidine carboxylic acid* NMDAICVT 1 μg/mouse 3 3 — *a known potent antagonist at the glutamate siteof the NMDA receptor Note: Compound I, at a dose of 30 μg/mouse, 2 outof 3 animals showed tremors without convulsions afterintracerebroventricular administration.

The data indicate that the compounds did not directly inhibit theeffects of NMDA activity when 30 ug/mouse was administeredintracerebrally.

The results hereinabove in the writhing test further demonstrate thatthe compounds of the present invention have analgesic activity for thetreatment of pain, including inflammatory pain, e.g., rheumatoidarthritis.

EXAMPLE 6

NMDA Induced Hyperalgesia

Holtzman male rats weighing 275 to 325 grams were prepared with lumbarintrathecal catheters under isoflurane anesthesia. The catheters wereexternalized on the back of the head. Four to five days after implant,the animals were employed.

NMDA administration was accomplished using a gear driven microinjectionsyringe connected to the spinal catheter by a length of calibrated PE-90tubing. The catheter plug was immediately replaced to avoid back flowand the rat was replaced in its testing box.

A modified Hargreaves box was used which allows the direction of afocused light beam on the underface of the paw through a glass surfaceupon which the rat stands. Surface temperature was maintained at 30° C.Withdrawal of the paw was taken as the response. Lack of response withintwenty seconds was cause to terminate the test and assign that score.

The rats were placed on the thermal escape box and allowed to acclimatefor 30 minutes prior to testing. A measurement was taken for eachhindpaw to establish an average baseline latency (counted as time=0).(2R)-2-(acetylamino)-N-[(4-fluorophenyl)methyl]-3-methoxypropanamidesolution, that is, test product in this experiment, was given at anintrathecal dose of 1 μg/10 μl 10 minutes prior to intrathecal NMDA. Acontrol group was given an identical amount of saline 10 minutes priorto intrathecal NMDA. Measurements were then made at 15, 30, 60, 120, 240and 360 minutes after intrathecal NMDA injection. General behaviorassessments were made during each period of observation and include:tactile allodynia (vocalization/agitation induced by light touch appliedto the body surface), spontaneous vocalization, biting and chewing ofbody surface, loss of hind limb placing and stepping reflex, loss ofhind limb weight bearing and loss of righting reflex.

The saline group (n=2) displayed a hyperalgesic effect with a baselinelatency of approximately 1—second dropping to about 7 seconds afterabout 45 minutes. The test product group (n=2) maintained a normalbaseline of about 14 second out to 20 minutes post NMDA injection andthen dropping in latency to approximately 10 seconds. The preliminarydata with the NMDA induced thermal hyperalgesic suggest that the2R-2-(acetylamino)-N-[(4-fluorophenyl)methyl]-3-methoxypropanamide hadmeasurable anti-hyperalgesic actions.

EXAMPLE 7

Sprague Dawley male rats weighing 275 to 325 grams was used in thisexperiment. In this experiment, the response to neuropathic pain wasdetermined. The neuropathic preparation used to induce an allodynicstate is the surgical procedure described by Kim and Chung in Pain,1992, 50,355–363 (1992) and outlined in Chaplain, et al. in J. Neurosci.Meth., 1994, 53, 355–363. Briefly, the left L₅ and L₆ spinal nerves wereisolated adjacent to the vertebral column and ligated with 6-0 silksuture distal to the dorsal root ganglion under isoflurane anesthesia.The rats were allowed a minimum 7 day postoperative recovery periodbefore placement in the study.

Testing groups consisted of 6 rats per group. Each group received testarticle,(2R)-2-acetyl-amino)-N-[(4-fluorophenyl)methyl]-3-methoxypropanamide(hereinafter “test article”), in one of three concentrations deliveredintraperitoneally; the high concentration was 50 mg/kg, the mediumconcentration was 30 mg/kg and the low concentration was 20 mg/kg. Onegroup of 6 rats received saline control solution at a volume equal tothat used for test article.

General behavioral assessments were made during each period ofobservation and include: tactile allodynia (vocalization/agitationinduced by light touch applied to the body surface), spontaneousvocalization, biting and chewing of body surface, loss of hind limbplacing and stepping reflex, loss of hind limb weight bearing, and lossof righting reflex. All assessments were noted as “present”, “absent” orranked according to a graded scale.

To assess tactile thresholds, rats were placed in a clear plastic, wiremesh-bottomed cage, divided into individual compartments. Animals wereallowed to accommodate and then baseline thresholds were taken prior todrug treatment. To determine the 50% mechanical threshold for pawwithdrawal, von Frey hairs were applied to the plantar mid-hindpaw,avoiding the tori (footpads). The eight von Frey hairs used aredesignated by [log (10*force required to bend hair, mg)] and range from0.4–15.1 grams. Each hair was pressed perpendicularly against the pawwith sufficient force to cause slight bending, and held forapproximately 6–8 seconds. A positive response was noted if the paw wassharply withdrawn. Flinching immediately upon removal of the hair wasalso considered a positive response. Absence of a response (“−”) wascause to present the next consecutive stronger stimulus; a positiveresponse (“+”) was caused to present the next weaker stimulus. Stimuliwere presented successively until either six data points were collected,or the maximum or minimum stimulus was reached. If a minimum stimuluswas reached and positive response still occurred, the threshold wasassigned an arbitrary minimum value of 0.25 grams; if a maximum stimuluswas presented and no response occurred, a maximum threshold value of 15grams was assigned. If a change in response occurred, either “−” to “+”or “+” to “−”, causing a change in the direction of stimuluspresentation from descending to ascending or vice-versa, four additionaldata points were collected subsequent to the change. The resultingpattern of responses were tabulated and the 50% response thresholdcomputer using the formula:log(threshold, mg×10)=Xf+kh

-   -   wherein:        -   Xf=value of the last von Frey hair applied;        -   k=correction factor based on response pattern (from            calibration table)    -   h=mean distance in log units between stimuli.

Based on observations on normal,—operated rats and sham-operated rats,the cutoff of a 15.1-g hair is selected as the upper limit for testing.

The test was performed to establish an average baseline value, countedas time 0; then again at 15, 30, 60, 120 and 240 minutes after thedosing by the control saline solution or the test article.

The results were as follows:

Four rats were examined at intraperitoneal (IP) doses of 30 to 100mg/kg.

One rat was given 100 mg/kg of the test article and within 15 minutesthe rat was laterally recumbent displaying seizures and bleeding fromthe nose. The animal was euthanized.

A second rat was given 90 mg/kg of the test article and within 15minutes the animal became catatonic and unable to right itself. Theanimal became flaccid and displayed severe exopthalmos. Thirty minuteslater there was no change and the animal was euthanized.

A third animal was given 60 mg/kg of the test article and within 15minutes the animal became catatonic and displayed abnormal ambulation.Severe exopthalmos was also noted. Thirty minutes later, the animal'sambulation appeared worse and it was subsequently euthanized.

A fourth rat was given 50 mg/kg of the test article. The rat appearedslightly catatonic which lasted 60 minutes. No other behavioral deficitswere noted.

A fifth rat was given 30 mg/kg of the test article IP and it displayedno behavioral deficit.

Fifteen mg/kg of the test article had previously been shown to have noobservable affect.

Using the Chung Model a dose dependent response was seen. The effectlasted approximately 2 hours after injection. Rats given the high doseof 50 mg/kg IP showed a threshold increase from 2 to 11 grams.Behaviorally 6 of 6 rats appeared sedated for approximately 1 hour postinjection. No other deficits were noted. Rats given 20 mg and 30 mg/kgtest article showed an increase in threshold from approximately 2 to 5grams. Four of 6 rats given 30 mg appeared sedated for approximately 1hour. No other deficits were noted. Previous study of 15 mg/kg showed noeffect on the Chung Model. Group comparisons using one-way ANOVAperformed on maximum effect, area under the curve and on specific timepoints (15 and 30 minutes post injection) showed no significantdifference between groups. The nonparametric Jonckheere Test of orderedalternatives was performed and showed a dose related difference at thep<0.05 level.

Test Article delivered intraperitoneally resulted in a significantreversal of tactile allodynia otherwise observed in the Chung model ofneuropathy. This model has historically been shown to be affected by anumber of clinically relevant agents, such as alpha 2 adrenergicagonists, NMDA receptor antagonists and N-type Ca channel blockers.Importantly, these observations occurred at doses that were believed tobe without significant effects upon competing behaviors (e.g., sedationor motor impairment).

The above preferred embodiments and examples are given to illustrate thescope and spirit of the present invention. The embodiments and examplesdescribed herein will make apparent to those skilled in the art otherembodiments and examples. These other embodiments and examples arewithin the contemplation of the present invention. Therefore, thepresent invention should be limited only by the appended claims.

1. A method for the treatment of migraine headaches in a patientcomprising administering to said patient a headache relieving effectiveamount of a compound of the formula:

wherein R is aryl lower alkyl, and R is unsubstituted or is substitutedwith at least one electron withdrawing group or electron donating group;R₁ is lower alkyl and R₁ is unsubstituted or substituted with anelectron donating group or electron withdrawing group; R₂ is hydrogen,lower alkyl, lower alkenyl, lower alkynyl, aryl lower alkyl, aryl, halo,heterocyclic, heterocyclic lower alkyl, lower alkyl heterocyclic, lowercycloalkyl, lower cycloalkyl lower alkyl, or Z—Y, R₃ is lower alkyl,lower alkenyl, lower alkynyl, aryl, aryl lower alkyl, halo,heterocyclic, heterocyclic lower alkyl, lower alkyl heterocyclic, lowercycloalkyl, lower cycloalkyl lower alkyl or ZY; wherein R₂ and R₃ may beunsubstituted or substituted with at least one electron withdrawinggroup or electron donating group and wherein heterocyclic in R₂ and R₃is furyl, thienyl, pyrazolyl, pyrrolyl, imidazolyl, indoyl, thiazolyl,oxazolyl, isothiazolyl, isoxazolyl; piperidyl, pyrrolinyl, piperazinyl,quinolyl, triazoyl, tetrazolyl, isoquinolyl, benzofuryl, benzothienyl,morpholinyl, benzoxazolyl, tetrahydrofuryl, pyranyl, indazolyl, purinyl,indolinyl, pyrazolindinyl, imidazolinyl, imidazolindinyl, pyrrolidinyl,furazanyl, N-methylindolyl, methylfuryl, pyridazinyl, pyrimidinyl,pyrazinyl, epoxy, aziridino, oxetanyl, or azetidinyl; Z is O, S or NR₆′;Y is hydrogen, lower alkyl, aryl, aryl lower alkyl, lower alkenyl, orlower alkynyl, and Y may be unsubstituted or substituted with anelectron donating group or an electron withdrawing group, or ZY takentogether is NR₄NR₅R₇, NR₄OR₅, or ONR₄R₇ R₄ and R₅ are independentlyhydrogen, lower alkyl, aryl, aryl lower alkyl, lower alkenyl, or loweralkynyl, wherein R₄ and R₅ are independently unsubstituted orsubstituted with an electron withdrawing group or an electron donatinggroup; and R₆′ is hydrogen or lower alkyl and R₆′ may be unsubstitutedor substituted with an electron withdrawing group or an electrondonating group; R₇ is COOR₈ COR₈, hydrogen, lower alkyl, aryl, or aryllower alkyl, which R₇ may be unsubstituted or substituted with anelectron withdrawing group or electron donating group; R₈ is hydrogen orlower alkyl, or aryl lower alkyl, and the aryl or alkyl group may beunsubstituted or substituted with an electron withdrawing group or anelectron donating group; and n is 1; wherein the electron withdrawinggroup and electron donating group are selected from the group consistingof halo, nitro, lower alkenyl, lower alkynyl, formyl, aryl,trifluoromethyl, aryl lower alkanoyl, hydroxy, lower alkoxy, loweralkyl, mercapto, lower alkylthio and lower alkyldithio.
 2. The methodaccording to claim 1 wherein R₂ is hydrogen.
 3. The method according toclaim 1 wherein R₂ is hydrogen, lower alkyl, aryl, aryl lower alkyl,heterocyclic, heterocyclic lower alkyl or ZY; and R₃ is lower alkyl,aryl, aryl lower alkyl, heterocyclic, heterocyclic lower alkyl or ZY;wherein R₂ and R₃ are independently unsubstituted or substituted withsaid electron withdrawing group or electron donating group.
 4. Themethod according to claim 3 wherein R₂ is hydrogen and R₃ is loweralkyl, aryl, aryl lower alkyl, heterocyclic, heterocyclic lower alkyl,or ZY; which R₃ may be unsubstituted or substituted with said electronwithdrawing group or electron donating group.
 5. The method according toclaim 4 wherein R₂ is hydrogen and R₃ is lower alkyl, which may beunsubstituted or substituted with said electron donating or electronwithdrawing group.
 6. The method according to claim 4 wherein R₃ islower alkyl which is unsubstituted or substituted with hydroxy or loweralkoxy or NR₄OR₅ wherein R₄, and R₅ are independently hydrogen or loweralkyl, R is aryl lower alkyl, which aryl group may be unsubstituted orsubstituted with said electron withdrawing group and R₁ is lower alkyl.7. The method according to claim 4 wherein R₃ is heterocyclic.
 8. Themethod according to claim 7 wherein heterocyclic is heteroaromatic. 9.The method according to claim 8 wherein R₃ is furyl, pyridyl, thienyl orthiazolyl.
 10. The method according to claim 6 wherein aryl is phenyl.11. The method according to claim 6 wherein aryl is phenyl and isunsubstituted or substituted with halo.
 12. The method according toclaim 1 wherein the compound is (R)-N-Benzyl-2acetamido-3-methoxy-propionamide;O-methyl-N-acetyl-D-serine-m-fluorobenzylamide;O-methyl-N-acetyl-D-serine-p-fluorobenzylamide;N-acetyl-D-phenylglycinebenzylamide; D-1,2-(N,O-dimethylhydroxylamino)-2 acetamide acetic acid benzylamide; orD-1,2-(O-methylhydroxylamino)-2-acetamide acetic acid benzylamide. 13.The method according to claim 1 wherein the carbon atom which issubstituted by R₂ and R₃ is in the D configuration.
 14. The methodaccording to claim 1 wherein Ar is unsubstituted aryl or arylsubstituted with said electron donating or electron withdrawing groupand wherein the compound has the formula:

and Q is lower alkoxy.
 15. The method according to claim 14 wherein Q ismethoxy.
 16. The method according to claim 14 wherein Q is methoxy andAr is unsubstituted aryl or aryl substituted with halo.
 17. The methodaccording to claim 14 wherein the carbon atom which is bonded to CH₂Q isin the D configuration.
 18. The method according to claim 14 wherein thecarbon atom which is bonded to CH₂Q is in the D configuration.
 19. Themethod according to claim 14 wherein Ar is unsubstituted aryl or arylsubstituted with halo.
 20. The method according to claim 1 wherein R isbenzyl which may be unsubstituted or substituted with an electronwithdrawing group or electron donating group.
 21. The method accordingto claim 1 where R₁ is methyl.
 22. The method according to claim 1wherein R is benzyl, R₁ is lower alkyl and R₂ is hydrogen.
 23. Themethod according to claim 22 wherein R₃ is CH₂Q, NR₄OR₅ or NR₄NR₅R₇,wherein Q is lower alkoxy, R₄ is hydrogen or alkyl containing 1–3 carbonatoms, R₅ is hydrogen or alkyl containing 1–3 carbon atoms and R₇ ishydrogen or alkyl containing 1–3 carbon atoms.
 24. The method accordingto claim 23 wherein R₃ is CH₂Q.
 25. The method according to claim 1wherein R₁ is methyl, R is benzyl, R₂ is hydrogen, and R₃ is CH₂Qwherein Q is methoxy.
 26. The method according to claim 1 wherein R₁ ismethyl, R is m-fluorobenzyl, R₂ is H and R₃ is CH₂Q, wherein Q ismethoxy.
 27. The method according to claim 1 wherein R₁ is methyl, R isp-fluorobenzyl, R₂ is H, and R₃ is CH₂Q wherein Q is methoxy.
 28. Themethod according to claim 1 wherein R₁ is methyl, R is benzyl, R₂ ishydrogen and R₃ is phenyl.
 29. The method according to claim 1 whereinR₁ is methyl, R is benzyl, R₂ is hydrogen and R₃ is N(CH₃)OCH₃.
 30. Themethod according to claim 1 wherein R₁ is methyl, R is benzyl , R₂ ishydrogen and R₃ is NH(OCH₃).
 31. The method according to claim 1 whereinR₁ is methyl, R is fluorophenyl, R₂ is H, and R₃ is CH₂Q, wherein Q ismethoxy.
 32. A method for the treatment of migraine headaches in apatient comprising administering to said patient a headache relievingeffective amount of a compound of the formula:

wherein R is aryl lower alkyl and R is unsubstituted or is substitutedwith at least one electron withdrawing group or electron donating groupselected from the group consisting of halo, nitro, lower alkenyl, loweralkynyl, formyl, aryl, trifluoromethyl, aryl lower alkanoyl, hydroxy,lower alkoxy, lower alkyl, mercapto, lower alkylthio, and loweralkyldithio; R₁ is methyl, and is unsubstituted or substituted with anelectron donating group or an electron withdrawing group selected fromthe group consisting of halo, nitro, lower alkenyl, lower alkynyl,formyl, aryl, trifluoromethyl, lower alkoxy carbonyl, aryl loweralkanoyl, hydroxy, lower alkoxy, lower alkyl, mercapto, lower alkylthio,and lower alkyldithio; R₂ is hydrogen, lower alkyl, lower alkenyl, loweralkynyl, aryl, aryl lower alkyl, halo, heterocyclic, heterocyclic loweralkyl, lower alkyl heterocyclic, lower cycloalkyl, lower cycloalkyllower alkyl, or ZY; R₃ is lower alkyl, lower alkenyl, lower alkynyl,aryl, aryl lower alkyl, halo, heterocyclic, heterocyclic lower alkyl,lower alkyl heterocyclic, lower cycloalkyl, lower cycloalkyl lower alkylor ZY; wherein R₂ and R₃ may be unsubstituted or substituted with atleast one electron withdrawing group or electron donating group andwherein heterocyclic in R₂ and R₃ is furyl, thienyl, pyrazolyl,pyrrolyl, imidazolyl, indolyl, thiazolyl, oxazolyl, isothiazolyl,isoxazolyl, piperidyl, pyrrolinyl, piperazinyl, quinolyl, triazolyl,tetrazolyl, isoquinolyl, benzofuryl, benzothienyl, morpholinyl,benzoxazolyl, tetrahydrofuryl, pyranyl, indazolyl, purinyl, indolinyl,pyrazolindinyl, imidazolinyl, imidazolindinyl, pyrrolidinyl, furazanyl,N-methylindolyl, methylfuryl, pyridazinyl, pyrimidinyl, pyrazinyl,epoxy, aziridino, oxetanyl or azetidinyl; Z is O, S, or NR₆′; Y ishydrogen, lower alkyl, aryl, aryl lower alkyl, lower alkenyl or loweralkynyl, and Y may be unsubstituted or substituted with an electrondonating group or an electron withdrawing group, or ZY taken together isNR₄NR₅R₇, NR₄OR₅, or ONR₄R₇; R₆′ is hydrogen or lower alkyl; R₄ and R₅are independently hydrogen, lower alkyl, aryl, aryl lower alkyl, loweralkenyl, or lower alkynyl, and R₄ and R₅ may be independentlyunsubstituted or substituted with an electron withdrawing group or anelectron donating group; R₇ is COOR₈, COR₈, hydrogen, lower alkyl, arylor aryl lower alkyl, which R₇ may be unsubstituted or substituted withan electron withdrawing group or electron donating group; R₈ is hydrogenor lower alkyl, or aryl lower alkyl, and the aryl or alkyl group may beunsubstituted or substituted with an electron withdrawing group or anelectron donating group; and n is
 1. 33. The method according to claim32 wherein R₁ is methyl which is unsubstituted.
 34. The method accordingto claim 32 wherein R is benzyl, which is unsubstituted or substitutedon the phenyl ring with said electron donating group or electronwithdrawing group.
 35. The method according to claim 33 wherein R isbenzyl, which is unsubstituted or substituted on the phenyl ring withsaid electron donating group or electron withdrawing group.
 36. Themethod according to claim 32 wherein R₂ is hydrogen.
 37. The methodaccording to claim 33 wherein R₂ is hydrogen.
 38. The method accordingto claim 34 wherein R₂ is hydrogen.
 39. The method according to claim 35wherein R₂ is hydrogen.
 40. The method according to claim 32 wherein R₃is a lower alkyl which is unsubstituted or substituted with an electrondonating group or electron withdrawing group selected from the groupconsisting of halo, nitro, carboxy, lower alkenyl, lower alkynyl,formyl, aryl, carboxyamido, trifluoromethyl, lower alkoxycarbonyl, aryllower alkanoyl, hydroxy, lower alkoxy, lower alkyl, amino, loweralkylamino, dilower alkylamino, aryloxy, mercapto or lower alkylthio.41. The method according to claim 33 wherein R₃ is a lower alkyl whichis unsubstituted or substituted with an electron donating group orelectron withdrawing group selected from the group consisting of halo,nitro, carboxy, lower alkenyl, lower alkynyl, formyl, aryl,carboxyamido, trifluoromethyl, lower alkoxycarbonyl, aryl loweralkanoyl, hydroxy, lower alkoxy, lower alkyl, amino, lower alkylamino,dilower alkylamino, aryloxy, mercapto or lower alkylthio.
 42. The methodaccording to claim 34 wherein R₃ is a lower alkyl which is unsubstitutedor substituted with an electron donating group or electron withdrawinggroup selected from the group consisting of halo, nitro, carboxy, loweralkenyl, lower alkynyl, formyl, aryl, carboxyamido, trifluoromethyl,lower alkoxycarbonyl, aryl lower alkanoyl, hydroxy, lower alkoxy, loweralkyl, amino, lower alkylamino, dilower alkylamino, aryloxy, mercapto orlower alkylthio.
 43. The method according to claim 35 wherein R₃ is alower alkyl which is unsubstituted or substituted with an electrondonating group or electron withdrawing group selected from the groupconsisting of halo, nitro, carboxy, lower alkenyl, lower alkynyl,formyl, aryl, carboxyamido, trifluoromethyl, lower alkoxycarbonyl, aryllower alkanoyl, hydroxy, lower alkoxy, lower alkyl, amino, loweralkylamino, dilower alkylamino, aryloxy, mercapto or lower alkylthio.44. The method according to claim 36 wherein R₃ is a lower alkyl whichis unsubstituted or substituted with an electron donating group orelectron withdrawing group selected from the group consisting of halo,nitro, carboxy, lower alkenyl, lower alkynyl, formyl, aryl,carboxyamido, trifluoromethyl, lower alkoxycarbonyl, aryl loweralkanoyl, hydroxy, lower alkoxy, lower alkyl, amino, lower alkylamino,dilower alkylamino, aryloxy, mercapto or lower alkylthio.
 45. The methodaccording to claim 37 wherein R₃ is a lower alkyl which is unsubstitutedor substituted with an electron donating group or electron withdrawinggroup selected from the group consisting of halo, nitro, carboxy, loweralkenyl, lower alkynyl, formyl, aryl, carboxyamido, trifluoromethyl,lower alkoxycarbonyl, aryl lower alkanoyl, hydroxy, lower alkoxy, loweralkyl, amino, lower alkylamino, dilower alkylamino, aryloxy, mercapto orlower alkylthio.
 46. The method according to claim 38 wherein R₃ is alower alkyl which is unsubstituted or substituted with an electrondonating group or electron withdrawing group selected from the groupconsisting of halo, nitro, carboxy, lower alkenyl, lower alkynyl,formyl, aryl, carboxyamido, trifluoromethyl, lower alkoxycarbonyl, aryllower alkanoyl, hydroxy, lower alkoxy, lower alkyl, amino, loweralkylamino, dilower alkylamino, aryloxy, mercapto or lower alkylthio.47. The method according to claim 39 wherein R₃ is a lower alkyl whichis unsubstituted or substituted with an electron donating group orelectron withdrawing group selected from the group consisting of halo,nitro, carboxy, lower alkenyl, lower alkynyl, formyl, aryl,carboxyamido, trifluoromethyl, lower alkoxycarbonyl, aryl loweralkanoyl, hydroxy, lower alkoxy, lower alkyl, amino, lower alkylamino,dilower alkylamino, aryloxy, mercapto or lower alkylthio.
 48. The methodaccording to any one of claims 32–47 wherein R₃ is lower alkylsubstituted by said electron donating group.
 49. The method according toclaim 48 wherein R₃ is lower alkyl substituted by lower alkoxy.